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The very very good Single axis tracker

Discussion in 'Renewable Energy' started by umer27, Mar 1, 2009.

  1. duffy

    duffy New Member

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    Now that I've explained it to you.

    You're welcome.
     
  2. Mike_2545

    Mike_2545 Super Moderator

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    Just because it took days for you to understand it, does not mean it would take that long for any one else.
    Words that you don't know, like gnomon, are easily looked up in a dictionary, or on line...dude
     
  3. umer27

    umer27 New Member

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    Anyone want to answer the questions now ?
     
  4. dave

    Dave New Member

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  5. duffy

    duffy New Member

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    I don't think he understood it until he logged on here and I mentioned that the Lorentz tracker is using a clock and calendar approach. Otherwise he would have said something about using a clock, and probably not even bothered with the 10W "sensor" panel since the day cycle can sync off the main panels.

    Matter of fact, he probably still doesn't understand it. But rather than admit to that, he claims it will take too long to explain. :rolleyes:
     
  6. umer27

    umer27 New Member

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    you are the genius .. we all know it now..

    I came here to ask questions about the electronics part, as I had lost touch, working as a programmer for a long time .. since no one seems to be looking at the questions .. Im wondering is it something I did or is nobody bothered to answer the questions at the end of my first post.

    Regarding explaining it.. The AVR has an on-board RTC , but we only use that for the first day .. When the tracker is in "Learning mode" . After the first day , it records all the values from the previous day (using machine learning algo here.. ) . Has 14 basic set data points , which is the best No. of steps for tracking. Then we use the Max power point tracker algo's like P & O , and maintain MPP for thr 10W solar panel , which in turn also keeps the Big panels at MPP operating range as well .. I don't see how this was important or relevant to the electronics questions I was asking.. duffy here seems to skip every time.
     
  7. duffy

    duffy New Member

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    Don't see how it was important or relevant?

     
  8. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    I think it was duffy who raised the point about using a clock and calendar to track the sun.

    It works with a fair degree of accuracy :)D), so why use an analog solar sensor. Is your solar array mobile? John
     
  9. umer27

    umer27 New Member

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    I can write a simple c program that would tell me the position of the sun from 2000 to 2050 , according to time of the day and an accuracy of 0.1 degees.. Sort of predicting where the sun would be.. BUT this method doesn't compensate for clouds, wind speed, and other factors.

    MPPT and related control schemes are immune of these factors to a much greater degree. I was reading a research paper , and P & O , worked very well. Infact, from the study they did, It had the best results. me and my team will also be conducting our own experiment. In May 2009, we will test at least 8 different control strategies, and write our own paper with the reading we get.

    As far as the other questions go ,

    1. im measuring the 10W solar panel voltage and current, for this im using a simple shunt, the INA128 instrumentation amplifier and reading the ADC value.any bright ideas on improving this setup are most welcome ...

    3. I plan to use the LMD 18200 motor driver , since my actuator's reqs are so small.. anyone know of any protective circuitry in addition with the thermal and current flags on the LMD 18200 , Plz let me know..

    4. Was getting problems with counting the pulses of the reed sensor, but now I think using a Schmitt trigger OR RC filter with ADC monitoring would work..

    Please remember , I dont want any hardware that I dont really want.. The circuit has to be super efficient..

    5. For the battery, I want two charging stages. A simple charge.. and a float charge that I can apply with PWM. to protect the battery from overcharging, I will use a switch .. (in the high or low side, haven't decided yet.. ) . I need Ideas for the switch. The switch will remain closed for extended periods of time, I also want to apply float charge via PWM , so I think I have to use a high side P-channel MOSFET.. help needed with this one..
     
  10. umer27

    umer27 New Member

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    readings* :p
     
  11. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    How does wind speed affect the direction of greatest intensity from the sun? Neglecting, of course, that your sensors are not being moved around.

    Assuming that one's shadow is a good indicator of the correct direction -- a subject that was covered well in the above posts -- do clouds cause one's shadow to move?

    What are some of the other variable factors that affect the position?

    Is this really a school competion?

    John
     
  12. umer27

    umer27 New Member

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    does it look like a school competition.. :p



    clouds increase the amount of diffused sunlight.. because of that , the best place for the panels to be might not be at 90 degrees from the normal of the surface of the panels ..

    go look at IV curves for solar panels ..

    why is everyone so interested in the tracking part and not the electronics ?
     
    Last edited: Mar 3, 2009
  13. umer27

    umer27 New Member

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    about that school competition thing..

    lets see here..
    The panels each at 250 Watts cost roughly, 750 US dollars each, we have 8 on the tracker ..

    We bought an ETA track from lorentz , that cost around 5000 Dollars excluding shipping..

    A sunny boy swr1700E grid tie inverter .. thats something like 1200 $ +

    Panels = 750 x 8 = 6000
    ETA track = 5000
    Sunny boy = 1200

    thats over 12000 dollars .. pretty good for a school project aye ?
     
    Last edited: Mar 3, 2009
  14. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    The tracking described so far is shadow based. Thus, your comments about the effects of wind, clouds, and "other factors" on shadows is related to the question. Although clouds certainly scatter sunlight, I suspect their effect on changing the position of shadows is considerably less, if at all.

    As for the matter of focusing on the electronics, given that the mechanicals will be essentially the same regardless of how the tracking is done, I don't recall that you have presented any workable model that does not depend on a shadow. Thus, it comes down to knowing what the electronics are supposed to do before attempting to design them.

    John
     
  15. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    $12,000 is really very little and is almost nothing for an industrial project. Just consider the solar-powered car and auto-navigating car competitions.

    Look that the price of toy airplanes and helicopters, as other examples.

    John
     
  16. bryan1

    bryan1 Well-Known Member

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    Eh Umer,
    As your saying your using a AVR why bother wasting a 10 watt PV panel for tracking when all you need to use is 2 green leds. Using that concept is so simple even a picaxe can do the job and it has. As far as returning the tracker to daylight position as soon as both leds cease to emit any voltage or the use of a CDS the tracker can return to the start. The red rock ones do work qutie well but do have problems and as far as simplicity and effectiveness you can go past 2 humble green led's

    Cheers Bryan
     
  17. umer27

    umer27 New Member

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    like I said , We'll be doing a study in may on which strategy is best... I'll keep you posted which method got the best results ..
     
  18. Pommie

    Pommie Well-Known Member Most Helpful Member

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    Can someone explain to me how orientating the panel at anything other than straight at the sun can produce more power? How can trees, clouds, UFOs etc cast a shadow in such a way that changing the angle of the panel will increase output? The only way I can see this having an effect is if the pivot point is not on the plane of the panel and so reorientation actually moves the panels laterally.

    Mike.
     
  19. umer27

    umer27 New Member

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    @ john ..

    what do you want me to do ..use money as wallpaper for the back of the panels.. so that the cost goes up and you consider it as an industrial project :p

    We have funding approval for as much as we deem necessary , please tell me, what other things I need to spend cash on ?
     
  20. umer27

    umer27 New Member

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    @mike ..

    No we're not moving the panels laterally .. our tracking is based on max power that the system can deliver .. pls look at VI curves for Solar cells .. The MPP is at the knee of the curve.. so, we orient the panels in such a way in which we get the max current and max power out of the system ..

    The chronological tracker , tracks the SUN , we track the point at which we get max power. Normally they would be oriented in the same direction.. I will run identical systems in parallel, and we'll know the effects of diffused sunlight,

    Wind has something to do with air mass , and less overall less solar radiation reaching the panels as a result. I'll post the link to a paper that talks about this ..

    One other thing,IF The chronological tracker is reset, or somehow, the batteries run out.. you would have to tell it the date and time again.. commercially I don't think thats something a company who say sells the tracker .. would be willing to do ..

    In our case.. we don't give it the time or date, Infact even the data it stores from which the tracker learns and adapts .. is in its non-volatile memory part.
     
  21. umer27

    umer27 New Member

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    about the use of sensors..

    Sensor based trackers try and find the brightest part in the sky. On a cloudy day , this may not be in the Sun's direction or the place where you can extract max power .. :)
     

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